System for downhole packing

ABSTRACT

An apparatus and method of forming a barrier to fluid flow behind a liner are provided. In one embodiment of the invention, a method includes the steps of conveying a tool to a position within a wellbore having a liner, the tool carrying a seal material, and injecting the seal material from the tool through the liner to form a barrier to fluid flow behind the liner. In another embodiment of the invention, the apparatus includes a housing having a chamber carrying a seal material, and a means for injecting the seal material through the wellbore liner.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 60/910,846 filed Apr. 10, 2007.

FIELD OF THE INVENTION

The present invention relates in general to wellbore or borehole operations and more particularly to a methods and systems for creating seals in a wellbore utilizing a tool element that emits sealing material to form a seal between the tubing and the wellbore.

BACKGROUND

As more oilfields become mature, the need for side tracking existing wells and through tubing completions to improve production from these aging wells increases. Through tubing expandables and slotted liners may be used for side tracking and through tubing completions. Typically, at some point in the well's life, it is desired to segment or compartmentalize the well for selective treatment of a zone or to prevent encroachment of an undesired fluid. Unfortunately, through tubing expandables and slotted liners make it difficult to segment or compartmentalize the wellbore. Conventional packers do not allow segmenting or compartmentalizing these wellbores without considerable expense.

Therefore, it is a desire to provide a system and method for providing a seal behind a wellbore liner.

SUMMARY OF THE INVENTION

Apparatus and methods of forming a barrier to fluid flow behind a wellbore liner are provided. In an embodiment of the invention, a method includes the steps of conveying a tool to a position within a wellbore having a liner, the tool carrying a seal material, and injecting the seal material from the tool through the liner to form a barrier to fluid flow behind the liner.

In an embodiment of the invention, an apparatus includes a housing having a chamber carrying a seal material, and a means for injecting the seal material through the wellbore liner. The seal material may react to the hydrocarbons present in the wellbore to form the barrier. The seal material may be thixotropic in nature and/or a swellable material to facilitate placement through the liner while forming a suitable sealing plug where desired.

The foregoing has outlined the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and aspects of the present invention will be best understood with reference to the following detailed description of a specific embodiment of the invention, when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic side view of an embodiment of the sealing method of the present invention; and

FIG. 2 is a further view of the sealing method illustrated in FIG. 1.

DETAILED DESCRIPTION

Refer now to the drawings wherein depicted elements are not necessarily shown to scale and wherein like or similar elements are designated by the same reference numeral through the several views.

As used herein, the terms “up” and “down”; “upper” and “lower”; and other like terms indicating relative positions to a given point or element are utilized to more clearly describe some elements of the embodiments of the invention. Commonly, these terms relate to a reference point as the surface from which drilling operations are initiated as being the top point and the total depth of the well being the lowest point.

FIG. 1 is a schematic side view of an embodiment of the sealing method of the present invention, generally denoted by the numeral 10. A portion of a wellbore 12 is completed with a liner 14. Liner 14 may include one or more openings or perforations 16 along its length. For clarity, liner 14 is depicted in FIGS. 1 and 2 with multiple openings 16. As used herein, liner 14 includes any tubing, liner or screen that has openings 16. Openings 16 may be formed therethrough prior to hanging the tubular in the wellbore 12 or in the wellbore with punches, explosive charges, mills, drills and the like. Liner 14 may be cemented or non-cemented. Examples of liners 14 include slotted, perforated, or predrilled liners, or a screen or a pre-packed screen. An annulus 18 is formed between liner 14 and the wall 20 of wellbore 12.

It is desired to seal annulus 18 in a region 22. In the first step of sealing method 10, a tool 24 is positioned within liner 14 proximate region 22 via conveyance 42. Tool 24 includes, but is not limited to, a housing 26 having a chamber 28 carrying a seal material 30, injection mechanism 32, and one or more ports 34 connected to chamber 28. Tool 24 may also include locating sub 38 and sealing members 40. Tool 24 may also include perforating guns, drilling mechanisms or cutting mechanisms suitable for creating an opening 16. Conveyance 42 may be an electric line, coiled tubing (CT), jointed tubing, a wireline or a slickline. Injection mechanism 32 includes piston 44 in communication with chamber 28. Injection mechanism 32 includes pressurized fluid 46 to hydraulically actuate or motivate piston 44 against chamber 28 to expel seal material 30 from chamber 28. Sealing members 40 are positioned about the ports 34 and are actuatable or hydraulically expandable to a position engaging liner 14.

Tool 24 may be constructed for multiple tubing sizes. Before tool 24 is positioned proximate region 22, tool 24 may need to be run through tubing 50 having bore 56 until it reaches region 52, which has a bore 58 greater than bore 56, where liner 14 is deployed. As tool 24 passes through tubing 50, sealing members 40 may actuate or hydraulically expand to engage liner 14 to help position tool 24 into this larger bore region 52.

In the second step of method 10, tool 24 is positioned proximate opening 16, or, if necessary, forms an opening 16 in liner 14 using conventional means. In the third step of method 10, sealing members 40 may actuate to a position engaging liner 14 to form a channel 54 between housing 26 and liner 14 for injecting the seal material 30 behind liner 14.

Referring now to FIG. 2, in the fourth step of method 10, a signal is sent to injection mechanism 32 to actuate the injection mechanism. The signal may be an internal signal within tool 24, a mud pulse, a wireless or wired transmission or the like. In the fifth step of method 10, injection mechanism 32 is actuated, and pressurized fluid 46 moves piston 44 through chamber 28 to eject seal material 30 from chamber 28. Tool 24 then expels seal material 30 via ports 34 through channel 54 to inject seal material 30 through liner 14, as indicated by the arrows. In the sixth step of method 10, seal material 30 reacts with hydrocarbons in annulus 18 and forms sealing plug 48 behind liner 14 within region 22. Sealing plug 48 may be formed circumferentially about liner 14.

To form sealing plug 48, seal material 30 must be suitable for injecting through aperture 16 and for setting into a sealing plug 48 in reaction with contact with hydrocarbons. Thus, it is desired that seal material 30 be thixotropic in nature so that it will set and become substantially “self-supporting” relatively quickly. It may further be desired for seal material 30 to be a swellable material, so as to seal openings 16 in region 22. The swellable property further facilitates sealing between wellbore 12 and liner 14. It may further be desired for seal material 30 to have a sufficiently high gel strength so as to remain where placed, yet allow for a degree of gravity-induced flow to the lower portion of region 22, for example in horizontal wellbores. It is noted that seal material 30 may include one or more of the desired properties. It is further noted, and will be recognized with the above description of the method, that sealing plug 48 may be formed in stages or by one or more seal materials 30. For example, a first seal material 30 being primarily thixotropic in nature may be injected through opening 16 into region 22 and then followed with a second swellable seal material 30. It may also be desired to inject spacing fluids, such as water or drilling fluid, after one or more seal material injections.

Examples of suitable seal material 30 include, without limitation, foamed cements; unfoamed cements containing smectic clays such as bentonite and attapulgite, unfoamed cements containing welan gum, aluminum and/or iron sulphate, and/or calcium sulfate as thixotropy agents, thermosetting polymers such as epoxy, vinylester, phenolic and polyester resins, and cross-linking polymer gels (possibly with an added thixotrope).

Swellable seal material 30 swells from an unexpanded state to an expanded state when it comes into contact with or absorbs hydrocarbons. The hydrocarbons may be present naturally in wellbore 12, or present in the formation surrounding wellbore 12 and produced into the wellbore.

Examples of suitable swellable seal material 30 and their corresponding triggering fluids (listed in parenthetical) include, without limitation: liquid hydrogel (hydrocarbon); Bacel® hardfoam (hydrocarbon); ethylene-propylene-copolymer rubber (hydrocarbon oil); ethylene-propylene-diene terpolymer rubber (hydrocarbon oil); butyl rubber (hydrocarbon oil); haloginated butyl rubber (hydrocarbon oil); brominated butyl rubber (hydrocarbon oil); chlorinated butyl rubber (hydrocarbon oil); chlorinated polyethylene (hydrocarbon oil); styrene butadiene (hydrocarbon); ethylene propylene monomer rubber (hydrocarbon); natural rubber (hydrocarbon); ethylene propylene diene monomer rubber (hydrocarbon); ethylene vinyl acetate rubber (hydrocarbon); hydrogenised acrylonitrile-butadiene rubber (hydrocarbon); acrylonitrile butadiene rubber (hydrocarbon); isoprene rubber (hydrocarbon); chloroprene rubber (hydrocarbon); and polynorbornene (hydrocarbon).

In the embodiment illustrated in FIGS. 1 and 2, tool 24 carries both seal material 30 and injection mechanism 32 to facilitate a single trip into the well to create sealing plug 48 behind liner 14. By providing both seal material 30 and injection mechanism 32 within tool 24, method 10 allows for the creation of sealing plug 48 without the need for separate surface devices to pump or deliver seal material 30 downhole to region 22. Tool 24 may further include aids, such as a source of heat or radiation, to facilitate or aid the setting of sealing plug 48. The viscosity of seal material 30 may be varied based on the desired isolation length.

From the foregoing detailed description of specific embodiments of the invention, it should be apparent that a system and method for downhole packing that is novel has been disclosed. Although specific embodiments of the invention have been disclosed herein in some detail, this has been done solely for the purposes of describing various features and aspects of the invention, and is not intended to be limiting with respect to the scope of the invention. It is contemplated that various substitutions, alterations, and/or modifications, including but not limited to those implementation variations which may have been suggested herein, may be made to the disclosed embodiments without departing from the spirit and scope of the invention as defined by the appended claims which follow. 

1. A tool for creating a barrier to fluid flow behind a wellbore liner, the tool comprising: a housing having a chamber carrying a seal material; and a means for injecting the seal material through the wellbore liner.
 2. The tool of claim 1, wherein the injecting means includes a motivation mechanism in communication with the chamber.
 3. The tool of claim 2, wherein the motivation mechanism comprises a pressurized fluid.
 4. The tool of claim 1, wherein the injecting means includes spaced sealing members, the opposed sealing members actuatable to a position engaging the wellbore liner to form a channel between the housing and the wellbore liner for injecting the seal material behind the wellbore liner.
 5. The tool of claim 1, wherein the seal material is a liquid when disposed in the housing.
 6. The tool of claim 1, wherein the seal material is a foam when disposed within the housing.
 7. The tool of claim 1, wherein the seal material forms a barrier to fluid flow in reaction to contact with hydrocarbons.
 8. A method for creating a barrier to fluid flow behind a wellbore liner, the method comprising the steps of: conveying a tool to a position within a wellbore having a liner, the tool carrying a seal material; and injecting the seal material from the tool through the liner to form a barrier to fluid flow behind the liner.
 9. The method of claim 8, wherein the seal material is liquid when disposed in the housing.
 10. The method of claim 8, wherein the seal material is a foam when disposed in the housing.
 11. The method of claim 8, further including the step of forming a channel between the housing and an inner surface of the liner for injecting the seal material behind the liner.
 12. The method of claim 11, wherein the step of forming a channel includes extending a seal mechanism from the tool into engagement with the liner.
 13. The method of claim 12, further comprising the step of forming an opening in the liner.
 14. The method of claim 13, wherein the step of injecting the seal material through the liner comprises the step of injecting the seal material through the opening.
 15. The method of claim 14, further comprising the step of conveying the tool from a first region of the wellbore with a first bore to a second region of the wellbore with a second bore, wherein the second bore is larger than the first bore and the liner is positioned within the second region.
 16. The method of claim 15, further comprising the step of extending the seal mechanism from the tool to position the tool within the second region.
 17. The method of claim 16, wherein the seal material is swellable.
 18. The method of claim 17, wherein the seal material swells from an unexpanded state to an expanded state when the seal material contacts hydrocarbons.
 19. The method of claim 18, wherein the seal material is thixotropic.
 20. The method of claim 19, further comprising the step of selecting a viscosity of the seal material based on a desired length of the barrier. 